Liquid heater



June 21, 1955 R. A. MAHAFFY ET AL LIQUID HEATER INVENTORS 425m A. MHHHFFY WJLLIQM YOUNG Filed Nov. 3

II'I'IIIIII Ill United States Patent LIQUID HEATER Reid A. Mahafiy, Cedar Grove, and William E. Young,

Ramsey, N. 3., assignors to Standard Packaging Corporation, New York, N. Y., a corporation of Virginia Application November 30, 1953, Serial No. 394,982

8 Claims. (Cl. 219-39) This invention relates to an apparatus for supplying a flow of liquid heated to a temperature causing the liquid to be harmfully affected when exposed to the atmosphere. This liquid may be oil of the type used for supplying heat to various kinds of industrial equipment at temperatures high enough to affect the oil undesirably if the oil is exposed to oxidizing conditions and which, therefore, must be used in a closed system so that the oil is shielded from air while at such temperatures.

One of the objects is to provide such an apparatus, or liquid heater, in a form which is compact, which shields the heated liquid from the atmosphere in a manner protecting the liquid against being harmfully affected, and which is reliable and safe for use in the presence of persons who are uninstructed in the maintenance and precautionary care required by prior art apparatus designed for the same kind of use. Other objects may be made apparent by the following disclosure of a specific example of the invention.

This example is illustrated by the accompanying drawings in which Fig. l is a vertical section, Fig. 2 is a crosssection taken on the line 2-2 in Fig. 1 and Fig. 3 is a cross section taken on the line 33 in Fig. 1.

As illustrated, a vertical, cylindrical, axially elongated, heater tank 1 has a vertical, cylindrical head tank 2 superimposed thereabove. spaced from the heater tank and is of larger diameter and less axial length than the heater tank. The two tanks are axially aligned and a rigid, vertical tube 3 extends through the top 4 of the heater tank and through the bottom 5 of the head tank and the latters top 6.

The tube 3 is rigidly fastened or connected fluid-tightly to the parts 4, 5 and 6 to form a rigid unit. The tube 3 is straight or linear and has ports 7 and 8 formed therethrough inside of the head tank 2 respectively adjacent to the latters bottom 5 and top 6. The tube connects the top portion of the heater tank with the bottom portion of the head tank and the top portion of the head tank with the atmosphere outside of the two tanks.

A liquid pump 9 is located in the heater tank 1 and has an outlet conduit 16, extending through the heater tank, and an inlet 11 which is open to the inside of the heater tank It. The heater tank has an inlet in the form of a conduit 12 extending to and opening to the inside of the heater tank 1 near to its bottom 13. This pump is of the rotary type and when rotatively driven, with the heater tank ful of liquid, this pump sends a forced liquid flow from near the heater tanks top 4 through a closed system which returns the liquid to the heater tank via the inlet conduit 12. The pump is fastened to the inside of the top 4 adjacent to which the pump is located. The pump, of course, sucks in liquid from a location near to the top of the heater tank, while the inlet conduit opens into the heater tank near to the latters bottom.

A tubular drive shaft 14 is operatively connected to the pump 9 and extends therefrom upwardly through the tube 3, in radially spaced relation thereto, to pro- This head tank 2 is upwardly 2,711,473 Patented June 21, 1955 vide an annular conduit, to beyond the tubes upper end and above the top 6. An air fan 15, of the centrifugal blade type, is mounted on the shaft 14 adjacent to the top 6 and an electric motor 16 has its shaft 17 connected to the shaft 14. This motor is located above the fan and close thereto. This motor is mounted on a platform 18 supported by columns 19 connected to the periphery of a casing top 20 spaced above the heater tanks top 4 and rigidly connected to the tube 3. This casing top cooperates with a casing side or wall 21 and a casing bottom 22 to form a casing surrounding the heater tank 1 in spaced relation thereto. The resulting space is used to confine a mass of thermal insulation 23 about the heater tank. Tie rods 24a extend between the parts 20 and 22 to strengthen the assembly. The parts 18, 20 and 22 may all be circular and concentric with the two tanks and the parts may have substantially equal diameters which are slightly but appreciably greater than the diameter of the head tank 2.

A plurality of vertical heat radiating fins 24 are radially arranged around the tube 3 and connected thereto between the top 20 and bottom 5 and extend between the latter from the one to the other. A cylindrical wall 25 encircles the head tank 2 in radially spaced relation thereto and the lower end of this wall extends somewhat below the bottom 5 and connects with a horizontal disk or battle 26 spaced below the bottom 5 and having a central hole 27. The wall 25 extends somewhat above the top 6, of the head tank, and connects with a similar horizontal disk or bafiie 28 spaced above the head tanks top 6 and having a central hole 29. The hole 27 has a diameter fitting the lateral dimensions of the fins 24, and the hole 29 is located just below the intake portion of the fan 15. Thus a space is defined around the head tank and through which air is circulated upwardly in a forced draft manner. The fan 15 throws the air radially outwardly, away from the motor 16, and the annular space between the platform 18 and the disk 28 may be protected by a perforated cylindrical wall 39.

The heater tank 1 has an immersion heater 31 suspended therein from the top 4, which may be done by hanging the heater from the pump housing. This heater is of the electric resistance type and it has electric power wires 32, insulated, of course, which must be run through the heater tank. This is effected by running the wires through conduits, or pipes, having straight, vertical portions 33 which extend fluid-tightly through the top 4, and outer straight, vertical portions 3 which extend to above the head tanks top 6, with these straight portions joined by vertically looped portions 35 located adjacently above the heater tanks top 4. A port 36 is formed through the conduit portion 33 adjacently below the heater tanks top 4. The wires 32 have spaced ceramic insulating beads spaced therealong which fit loosely inside of the conduits and the upper ends of the latter are exposed to the atmosphere. Thus the ports 36 serve to vent the tank 1, as an added safety feature, and the liquid, of course, may rise in the conduit portions 34 to the level established by the liquid level in the head tank 2. The top of the portions 34 should terminate safely above this level.

The apparatus is filled with the oil, or other liquid, through an inlet 37 about half way up the side of the head tank. This inlet has a cap or plug 38 by which it is closed after filling. Liquid is poured in to fill the heater tank and the head tank until overflow shows that the level of the inlet 37 is attained. Venting is by way of the two tubes described, air or other gas being free to travel through and out from the tops of these tubes. The space above the liquid level in the head tank is adequate to accommodate all of the thermal expansion of the liquid. After use or whenever desired the apparatus may bedrained through a normally closed outlet 39 opening through the heater tanks bottom 13.

In operation the motor 16 is operated to drive the pump 9 and the fan 15 while the heater 3); is powered through the wires 32 to maintain the desired operating temperature of the oil or other liquid. The heater may be controlled by a suitably located, thermo-responsive, device 40, if desired. The liquid is forcibly driven from the heater tank and returned when the apparatus supplies a closed system. Expansion and contraction of the liquid, and the necessary venting, are amply provided, as already described, and the apparatus is reliably safe respecting venting.

The liquid in the head tank is continuously heated by the liquid in the tube 3 but this tube is continuously cooled by radiation from the fins 24 and the head tank is continuously cooled by the forced draft of air drawn around the head tank by the fan 15 which, in turn, throws the resulting heated air radially away from the motor 16. The cooling is adequate to maintain the temperature of the liquid in the head tank well below the operating temperature of the heater tank liquid, and below a temperature which would cause harm to the liquid due to its being exposed to the atmosphere through the top of the tube and the ports 8. The liquid rises in each power wire tubes portion 34, to the level of the liquid in the head tank, and the area here which contacts the atmosphere, through the openings where the wire 32 must leave, is very small since the conduits need be only large enough in diameter to house the wires and their insulation while leaving a small venting passage. Further, the length of the power wire conduits provides for extensive heat radiation loss while the loop portions 35 prevent thermosiphon effects from agitating the liquid so as to carry hot liquid more directly to the level in the portions 34. Each loop is in the path of air drawn through the hole 27, and incidentally along the fins 24, so that the loops are also cooled somewhat by convection, as are these fins.

Possibly entrapped air or other gas is continuously vented, while expansion and contraction is safely permitted, at all times without the highly heated liquid contacting the atmosphere. By interlocking the fan and pump motor and heating power lines, improper operation may be made impossible. Skilled maintenance and operation is unnecessary. The head tank liquid at all times maintains a hydraulic head or pressure on the liquid in the heater tank so that there is very little chance for the pump forcing out anything but a flow of solid liquid free from entrapped gas or air, provided, of course, that the liquid in the system is not heated excessively so as to form vapors, and so long as a suthcient quantity of liquid is maintained in the system.

The heater 31 may have exposed and uninsulated resistance wire supported by a ceramic tube and directly contacting the liquid to be heated, when this liquid is a dielectric such as oil. Also, in such a case, the power wires need not be insulated from contact with the liquid in the conduits carrying the wires from the heater tank. The head tanks top ti may have one or more vent holes, if desired, formed therethrough, so as to aid, or possibly replace, the venting action previously described.

it is to be noted that the liquid, being heated, itself serves to seal both the rotary shaft driving the pump inside of the heater tank, and the power lines for the heater which is also inside of the heater tank. The top surfaces of the liquid which are exposed to the atmosphere are, of course, relatively cool so that the liquid is not harmed by contact with the atmosphere.

We claim:

1. A heater for a supply of liquid which is harmfully affected when exposed to the atmosphere at the heaters operating temperature, the heater including a heater tank, means for heating liquid in the tank to said temperature, a head tank located over the heater tank, a conduit interconnecting the two tanks so that solid liquid is maintained in the heater tank by liquid in the head tank, the latter having a vent passage which is open to the atmosphere, and means for cooling the head tank to prevent it from being heated by the heater tank to temperatures high enough to harmfully affect the liquid in the head tank and open to the atmosphere through the vent passage.

2. A heater for a supply of liquid which is harmfully affected when exposed to the atmosphere at the heaters operating temperature, the heater including a heater tank, means for eating liquid in the tank to said temperature, a head tank located over the heater tank, a conduit interconnecting the two tanks so that solid liquid is maintained in the heater tank by liquid in the head tank, the latter having a vent passage which is open to the atmosphere, and means for cooling the head tank to prevent it from being heated by the heater tank to temperatures high enough to harmfully affect the liquid in the head tank and open to the atmosphere through the vent passage, the heating means comprising an electric resistance heater located inside of the heater tank and having electric power supply wires, and a tube connected with the heater tank and through which the electric power supply wires pass and which extends upwardly to a level above the level of liquid in the head tank and which tube is formed into a vertical loop at a location outside of the heater tank so as to prevent circulation of liquid therein upwardly due to thermosiphon effects, the outer end of the tube being open to the atmosphere.

3. Apparatus for supplying a forced flow of liquid heated to a temperature causing the liquid to be harmfully affected when exposed to the atmosphere, the apparatus including a heater tank, means for heating liquid in the tank to said temperature, a head tank located over the heater tank, a tube extending substantially vertically through the top and bottom of the head tank and the top of the heater tank and having passages opening from the tubes inside into the upper and lower portions of the head tank and above the top and outside of the head tank, a liquid supply force pump located inside of the heater tank below the lower end of the tube, a drive shaft connected to the pump and extending upwardly through the tube and beyond its upper end, an air fan connected to the upper end portion of the drive shaft above the head tank, a driving motor connected to the shafts upper end portion and located above the head tank, a wall surrounding the head tank and in spaced relation to its outside and through which the fan forces air to cool the head tank, and liquid inlet and outlet conduits for the heater tank with the outlet conduit connected with the outlet of the pump so that the heated liquid is forced thereto for use in a closed system, the cooled head tank venting upwardly through the tube to the atmosphere and preventing the development of material pressure in the heater tank.

4. Apparatus for supplying a forced flow of liquid heated to a temperature causing the liquid to be harmfully affected when exposed to the atmosphere, the apparatus including a heater tank, means for heating liquid in the tank to said temperature, a head tank located over the heater tank, a tube extending substantially vertically through the top and bottom of the head tank and the top of the heater tank and having passages opening from the tubes inside into the upper and lower portions of the head tank and above the top and outside of the head tank, a liquid supply force pump located inside of the heater tank below the lower end of the tube, a drive shaft connected to the pump and extending upwardly through the tube and beyond its upper end, an air fan connected to he upper end portion of the drive shaft above the head ank, a driving motor connected to the shafts upper end portion and located above the head tank, a wall surrounding the head tank and in spaced relation to its outside and through which the fan forces air to cool the head tank, and liquid inlet and outlet conduits for the heater tank with the outlet conduit connected with the outlet of the pump so that the heated liquid is forced thereto for use in a closed system, the cooled head tank venting upwardly through the tube to the atmosphere and preventing the development of material pressure in the heater tank, the heating means comprising an electric resistance heater located inside of the heater tank and having electric power supply wires, and a tube connected with the heater tank and through which the electric power supply wires pass and which extends upwardly to a level above the level of liquid in the head tank and which tube is formed into a vertical loop at a location outside of the heater tank so as to prevent circulation of liquid therein upwardly due to thermo-siphon eiiects, the outer end of the tube being open to the atmosphere.

5. A liquid heater including a heater tank, a head tank superimposed on the heater tank in upwardly spaced relation thereto, a rigid substantially vertical tube extending through the top of the heater tank and the bottom and the top of the head tank and rigidly fastened fluidtightly to these tops and this bottom in each instance, the tube being substantially straight and having ports formed therethrough inside of the head tank adjacent to the head tanks top and bottom, a liquid pump located in the heater tank and having an outlet conduit extending through the heater tank and an inlet open to the inside of the heater tank, the latter having an inlet, a drive shaft connected with and extending from the pump upwardly through the tube to beyond the latters upper end, an air fan fastened to the drive shaft above the head tank, a motor connected to the drive shaft above the fan and means for mounting the motor above the head tank, heat radiatin fins substantially vertically arranged between the two tanks and connected to the tube therebetween, a housing enclosing the head tank in spaced relation thereto and having a bottom and top each formed with a hole encircling the tube in radially spaced relation thereto. and means for heating liquid in the heater tank, the upper end portion of the tube being open to the atmosphere and venting both tanks.

6. A liquid heater including a heater tank, a head tank superimposed on the heater tank in upwardly spaced relation thereto, a rigid substantially vertical tube extending through the top of the heater tank and the bottom and top of the head tank and rigidly fastened fluid-tightly to these tops and this bottom in each instance, the tube being substantially straight and having ports formed therethrough inside of the head tank adjacent to the head tanks top and bottom, a liquid pump located in the heater tank and. having an outlet conduit extending through the heater tank and an inlet open to the inside of the heater tank, the latter having an inlet, a drive shaft connected with and extending from the pump upwardly through the tube to beyond the latters upper end, an air fan fastened to the drive shaft above the head tank, a motor connected to the drive shaft above the fan and means for mounting the motor above the head tank, heat radiating fins substantially vertically arranged between the two tanks and connected to the tube therebetween, a housing enclosing the head tank in spaced relation thereto and having a bottom and top each formed with a hole encircling the tube in radially spaced relation thereto, and means for liquid in the heater tank, the upper end portion the tube being open to the atmosphere and venting both tanks, the heating means being electrically powered and having power wires, and a conduit passing through the heater tank and carrying the wires therethrough, the wires being inside of this conduit and the latter hava substantially vertical portion extending through the heater tank and through which portion a port is formed adjacent to the inside of the top of the heater tank and having a portion extendin upwardly to above the level liquid in the head tank and thereabove being open to the atmosphere and having a portion formed into a vertical loop adjacentb above the heater tank.

7. A liquid heater including a heater tank, a liquid pamp located inside of the tank, a tube extending upwardly from the tank and up into which the liquid may rise, and a drive shaft for the pump extending therefrom through the tube and sealed by liquid in the tube.

8. A liquid heater including a heater tank, electric heating means located inside of the tank, a tube extending from the tank upwardly and up into which the liquid may rise, and electric power wires extending from said means through the tube and sealed by liquid in the tube.

References Cited in the file of this patent UNlTED STATES PATENTS 2,079,989 Delano May 11, 1937 2,091,838 Staak Aug 31, 1937 2,203,425 Welch June 4, 1940 

